Clear QList that is being used by QSerial - c++

Question

I have the following bit of code:
QTimer *timer = new QTimer(this);
connect(timer, SIGNAL(timeout()), this, SLOT(updatecommstatus()));
timer -> start();
void MainWindow::updatecommstatus()
{
const auto infos = QSerialPortInfo::availablePorts();
for (const QSerialPortInfo &info : infos) {
QString s = QObject::tr("Port: ") + info.portName() + "\n"
+ QObject::tr("Location: ") + info.systemLocation() + "\n"
+ QObject::tr("Description: ") + info.description() + "\n"
+ QObject::tr("Manufacturer: ") + info.manufacturer() + "\n"
+ QObject::tr("Serial number: ") + info.serialNumber() + "\n"
+ QObject::tr("Vendor Identifier: ") + (info.hasVendorIdentifier() ? QString::number(info.vendorIdentifier(), 16) : QString()) + "\n"
+ QObject::tr("Product Identifier: ") + (info.hasProductIdentifier() ? QString::number(info.productIdentifier(), 16) : QString()) + "\n"
+ QObject::tr("Busy: ") + (info.isBusy() ? QObject::tr("Yes") : QObject::tr("No")) + "\n";
if (QString::number(info.vendorIdentifier(), 16) == "16d0" && QString::number(info.productIdentifier(), 16) == "650")
{
ui->label_commport->setText(info.portName());
}
else
{
ui->label_commport->setText("COM Error");
}
}
}
It is utilising QSerial to display all the available COM ports info. I want to display the portName in a label when certain vendorIdentifierand and productIdentifier match some number.
The above code works well when the device is plugged in (my label displays the right information). But I want to have it when I unplug it that the label displays COM Error. This part does not work. The above code is being targetted by a QTimer and updated, but the Qlist infos is not clearing. Basically, how can I clear this Qlist ? infos.clear(); does not work.

Answer 1

As #lucaAngiolini alluded to in his comment, the scope of you label update seems wrong. I think your trying to do actually compile all available ports into a string, and then set the label thereafter.
void MainWindow::updatecommstatus()
{
const auto infos = QSerialPortInfo::availablePorts();
QStringList comport_labels;
if (infos.empty())
comprt_labels << "COM Error";
for (const QSerialPortInfo &info : infos) {
QString s = QObject::tr("Port: ") + info.portName() + "\n"
+ QObject::tr("Location: ") + info.systemLocation() + "\n"
+ QObject::tr("Description: ") + info.description() + "\n"
+ QObject::tr("Manufacturer: ") + info.manufacturer() + "\n"
+ QObject::tr("Serial number: ") + info.serialNumber() + "\n"
+ QObject::tr("Vendor Identifier: ") + (info.hasVendorIdentifier() ? QString::number(info.vendorIdentifier(), 16) : QString()) + "\n"
+ QObject::tr("Product Identifier: ") + (info.hasProductIdentifier() ? QString::number(info.productIdentifier(), 16) : QString()) + "\n"
+ QObject::tr("Busy: ") + (info.isBusy() ? QObject::tr("Yes") : QObject::tr("No")) + "\n";
if (QString::number(info.vendorIdentifier(), 16) == "16d0" && QString::number(info.productIdentifier(), 16) == "650")
{
comport_labels << info.portName();
}
else
{
comport_labels << "COM Error";
}
}
ui->label_commport->setText(comport_labels.join(","));
}